Search by keywords or author
• Vol. 1, Issue 4, 040501 (2019)
Denis Baranov
Author Affiliations
• Chalmers University of Technology, Gothenburg, Sweden
• show less

Abstract

A new kind of electromagnetic wave, combining the properties of propagating and evanescent waves, is discovered theoretically in a paper by E. Narimanov, published in this issue of Advanced Photonics. The commentary provides context for Narimov’s paper.

The most common type of waves of any nature—either electromagnetic or acoustic—are the so-called uniform plane waves. They exhibit uniform phase oscillations in the propagation direction, and carry energy along that direction. When projection of the wavenumber exceeds the maximal allowed value $k0$, determined by the material properties of the medium (for example, $k0=nω/c$ in isotropic media for electromagnetic waves, where $n$ is the refractive index), the wave becomes evanescent—its wavevector acquires an imaginary component and an exponentially decaying field profile. The energy in such a wave is carried in the direction of phase oscillations, with zero energy flux in the direction of attenuation. These two properties (phase oscillations and exponential attenuation) can be combined in one direction by a wave propagating in a lossy medium (for example, in a Drude metal), but such a wave will still carry energy along its “main” direction.

Copy Citation Text
Denis Baranov. Seeing a ghost: hybrid waves in anisotropic crystals[J]. Advanced Photonics, 2019, 1(4): 040501